CN1247404A

CN1247404A - Efficiency and application of high-frequency electricity

Info

Publication number: CN1247404A
Application number: CN 98121481
Authority: CN
Inventors: 李成亮
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-09-29
Filing date: 1998-09-29
Publication date: 2000-03-15

Abstract

The present invention relates to the efficiency and application of high-frequency electricity, which features that the high-frequency can be used for electric generator, transformer and electric motor by reducing pitch and serially or parallelly connecting high-capacity capacitor to further increase the power factor and output power of electric generator.

Description

The efficient of high-frequency electrical and application

How to improve the efficient of generator---increase frequency and dwindle resistance, just increase number of poles, shortening of pitch, improve power factor CoS θ by serially adding electric capacity again

Why is the frequency of power generator all 50 hertz? in China, and even all adopt this cycle in the world many countries, reason is to adopt higher frequency that higher impedance has just been arranged, and influences the output current of generator, in most generating equipments in thermal power plant, the number of poles of generator is 2 utmost points, and 3000 rev/mins, frequency is 50 hertz, because pitch is bigger, copper consumption is many, temperature rise, copper resistance consumption RI ²Bigger, so the copper consumption volume of the transformer that transmits electric power is all bigger, and the copper consumption volume of respective electrical motivation is all bigger.

In order to address these problems, must change the coiled multipolarity, short pitch line bag, as: 2 utmost points change 12 utmost points into, simultaneously also corresponding 12 utmost points that make into of rotor number of poles, when the rotating speed of generator kept 3000 rev/mins: its frequency just increased to 300 hertz, induction reactance nearly doubles simultaneously, the corresponding increase of phase angle difference, and power factor (PF) CoS θ just reduces, the corresponding increase of exciting curent goes to overcome but can serially add large bulk capacitance in the generator outside.

The purpose of this invention is to provide a kind of improved shortening of pitch, increase frequency, reduce temperature, reduce a kind of generator of the raising electrical power of copper consumption and copper resistance consumption.

The present invention is achieved in that the rotating speed that can not reduce generator, should keep original fast 3000 rev/mins, the output voltage that just keeps former generator should dwindle the length of the copper cash pitch in the stator winding simultaneously, and not reduce its number of turn, 2 utmost points change 12 utmost points into exactly, the frequency after changing extremely

, be original 50 hertz 6 times therefore, and should suitably improve power factor (PF) CoS θ by method in the outside series capacitance of generator, reduce the inductive reactance xl in the high-frequency electrical, rather than increase the internal resistance R in the lead, angular difference θ is reduced.

The present invention is because dwindled the length of copper cash pitch in the stator winding, thereby the copper consumption and the resistance of whole generating machine have been reduced, and frequency is brought up to 6 times, again because each serially adds one group of jumbo electric capacity in the generator outside, so realize generator electric current in the course of the work easily, the standard output of voltage requires (change the size of capacitance, just can change phase difference and output current).

Make 2 utmost points respectively with the permanent magnet generator of 2 24 grooves now and 12 utmost points compare, 50 revolutions per seconds of the rotating speeds of their prime mover are constant, the size of stator and rotor, the length diameter entirely, but 12 utmost points is short-chorded coil, pitch is:

And the pitch of 2 pole generators is 9 grooves (1 groove is striden 10 grooves), and copper consumption is mutually far short of what is expected as can be seen, and their frequency is respectively 50 hertz and 300 hertz:

Is their voltage identical so? wherein one:

The voltage of 2 pole generators, E _{2 utmost points}=4.44fW φ 10 ^-8(f=50 circular frequency)

If every groove number of turn all is W, 22 utmost points can be around the 6W circle so,

E _{2 utmost points}=4.44 * 50 * 6W φ 10 ^-8

[the magnetic strength B that φ equals rotor multiply by the polarity area S of the every utmost point of rotor,

(d is a root diameter, and L is a rotor length) so

E _{2 utmost points}=222 * 3WBdL π * 10 ^-8=666WBdL π * 10 ^-8

E _{12 utmost points}=4.44 * 300 * 6W φ * 10 ^-8

∴ E _{12 utmost points}=4.44 * 300 * 6WBLd π/12 * 10 ^-8=222 * 3WBdL π * 10 ^-8=666WBLd π * 10 ^-8

Their output voltage was constant after this had illustrated and has changed extremely with the volume generator.

Can their output current become so? answer is yes, can reduce one times, how to reduce? reason is that impedance doubles, have and have no idea to reduce impedance and make the electric current before output current keeps not changing frequently even exceed original output current? it also is sure answering, have, exactly by serially adding jumbo electric capacity, to offset the induction reactance in the circuit in each of generator outside, thereby improved power factor (PF) CoS θ, improved the generator output current.

Did why when frequency was brought up to 300 hertz, impedance ratio just double originally? have a test to can be used as reference now, a permanent magnetism small generators, its number of poles are 12 utmost points, and the polarity area is 1,5cm ²When rotating speed was 50/6 revolutions per second: its frequency was 50 hertz, and voltage is 6 volts, and its short circuit current is 1.4 peaces, when rotating speed is 50 revolutions per seconds, its frequency is 300 hertz, and voltage is 36 volts, and short circuit current is 4.5 peaces, their internal resistance 2.5 Ω are constant, so just can calculate their impedance Z n=V/I respectively, V/I=6/1.4=4.285 Ω, V/I=36/4.5=8 Ω.

After analysis generator changed extremely more now, resistance reduced half later motive power merit that they consume and what efficient separately has change.

The power factor (PF) variation of triangle projective planum impedance diagram and efficiency change situation give to discuss according to key issue solved by the invention when describing generator rotor structure figure one and stator track short circuit in detail below in conjunction with figure I.

In rectangular coordinate, oy represents voltage direction, and ox represents the inductance direction, and when frequency was 50 hertz, 2 pole generator lead internal resistance R were the AB among the figure two, and impedance is Zn, and induction reactance is X _L, θ represents the angle that sense of current OA lags behind than voltage direction oy, and when frequency was 300 hertz, lead internal resistance R was the A ' B ' among the figure three, and impedance is Zn ', and induction reactance is X _L'=2X _L, θ ' is the angle of sense of current OA ' than voltage direction oy ' hysteresis.

The available power that generator is done during short circuit all is the power that the generator internal resistance is consumed as can be known.

Be RI respectively ²And R ' I ' ², because R '=R/2,

So, RI ²: R ' I ' ²Equal That is:

In other words, generator is when short circuit, when the output total work VI of generator is 300 circular frequencies during 50 circular frequencies 2 times of generator output total work VI, but 8 times of the motive power merit that generator is consumed when 50 circular frequencies also the have been described motive power merit that generator is consumed when being 300 circular frequencies.When their efficient is 50 circular frequencies respectively

During with 300 circular frequencies

Here not too suitable with VI as the output work of generator.

When we serially add large bulk capacitance in the generator outside, allow ultrasonic-frequency rotory generator that the output current of low-frequency generator is arranged, go to observe the situation of their internal resistance consumed works again: in figure four, impedance this moment remains unchanged, output current and output apparent power are VI, and be just constant.Just because , the internal resistance wasted work is

, be RI ²Half, become 300 circular frequencies in other words after, keep original output voltage and output current then can reduce the generator internal resistance consumption of half, the efficient of this moment is:

, for large-scale generator, save the internal resistance wasted work rate of half, also be a no small numeral, as: one 50,000 kilowatts generator can save 250 kilowatts temperature rise wasted work rate, has saved 0.5% of gross power.

[someone is bound to ask: " the total work VI during generator short circuit can not be as the output work of generator, the power that should be exported as generator with VICoS θ ", in fact VICoS θ is exactly the power that internal resistance consumes, i.e. RI ², this is skimble-skamble repetition.The most effective relatively be exactly allow 50 frequently and 300 frequently generator outsides add respectively pure resistance R Ω with

, do work to resistance; This moment their impedance Z _nThe same, inside and outside pure resistance with the same, all be 2R, at this moment their power factor (PF) is the same,

Output current is the same , power output is VI ₀CoS θ is constant, but the power that external resistor consumes is really different, is respectively P _{50 frequently}=RI ₀ ²

, the efficient of their external actings respectively is like this

U As seen change the efficient of the efficient of frequently later generator, and the temperature rise of generator has reduced much greater than the generator before not changing frequently.]

In addition, the power factor of generator also has relation with the load of being supplied with, pure resistance type load can improve the power factor (PF) of whole circuit, all motor can improve the power factor (PF) of whole circuit equally, so the power factor (PF) that single power factor (PF) of seeing ultrasonic-frequency rotory generator from ground is lower than low-frequency generator does not have any meaning, in addition, also has power factor (PF) low more, the motive power that it consumed is also few more, can be from the efficient of generator Middle proof.

So, say that motor also can improve the power factor (PF) of whole circuit why? (essence of so-called power factor (PF) is exactly the angular difference of voltage and current).Because have in the motor than " back electromotive force " of supply voltage more than 80%, in fact the direction of back electromotive force and primary voltage is not to differ 180 °, but one greater than 90 ° of obtuse angles, the size at this obtuse angle is that the ratio according to the size of supply voltage and back electromotive force and inductance and coil internal resistance goes to determine, figure five can illustrate the motor work principle, be that example: OA is that to make voltage Oe outward be the back-emf of motor to motor with the individual event, OB is the voltage that closes of OA and Oe, OP lags behind the electric current that closes that closes voltage OB, its phase angle

OF is the angular difference of hysteresis voltage OA when empty load of motor rotates oe and OA near antiphase, and the power factor (PF) CoS θ when also being empty load of motor is when load during for maximum: back-emf oe and to close electric current op opposite.

True and theory proves all that some internal resistance is the big more motor of the higher inductance of small frequency more, has higher efficient, from figure ID as can be known, close voltage OB size and Orientation and

The cosine function value has much relations, the OP electrical power few more (VICoS β) that the OA motor is consumed that lags behind more, and back-emf oe work is many on the contrary.Because the angle of Oy and oe is to dwindle along with the increase of inductance, closing voltage OB just increases, OB is big more, and the electric current OP that closes just increases, motor work rate just increases for oeopCoS180 °, Here it is changes the meaning that low frequency is a high frequency, improving power factor (PF) for motor dwindles the phase angle difference of electric current and voltage and does not have what meaning, the power of motor acting only with self back-emf and close current related system, it doesn't matter and with power factor (PF) CoS θ, CoS θ is big more, the electric energy VICoS θ that motor consumes is many more, and efficiency of motor is low more, in figure Id

Improving power factor (PF) CoS θ thus is favourable for generator, and for motor anti-meaning is arranged, and (explanation of giving an example: if the copper cash of motor is used tungsten filament instead and made, the formed electromagnetic field of Ampere currents is very weak, that is:

Very big, power factor (PF) CoS θ=0.99, so, the power consumption of this motor is: VICoS θ=0.99VI ≈ VI, and the motor work is still eI, its efficient is The winding back emf e that inductance is very little is also very little).High-frequency electrical can be dwindled the volume of transformer in the energy transfer process of transformer, do not influence the characteristic of transformer and the no-load voltage ratio formula E=4.44fw φ 10 according to self induction electromotive force ^-8

Formula E is a self induction electromotive force, should be mutual with the output voltage V of generator, φ is the magnetic flux of core section, f is a frequency, W is the number of turn of primary winding, when E and φ are constant, frequency f is big more, number of turn W is more little, and frequency f improves 6 times, and the number of turn is just dwindled 6 times, same secondary coil also dwindles 6 times and (should take into account frequency here and improve 6 times, whether the magnetic loss of iron core increases) thus utilize high-frequency current, in twice transformation from the power plant to the Subscriber Unit, can reduce 3-5 doubly copper consumption and with the copper loss and the iron loss of iron amount and transformer.

The use of the alternating current of 300 circular frequencies in motor:

In three induction machines, what of each number of turn are according to formula E is a supply voltage, and during delta connection, E is 380 volts, and E is 220 volts during the bifurcation wiring, f---frequency, and B is a stator magnetic flux intensity, B _{On average}=6000 Gausses, the magnetic flux area of the every utmost point of S=.

When frequency is 300 hertz, for with the motor of volume with rotating speed, its number of poles should enlarge 6 times, just the polarity area has dwindled 6 times, original 2 utmost point motors of 50 circular frequencies, its rotating speed of motor that changes 300 circular frequencies into is constant, and the pitch of different is coil has shortened a lot, has saved copper loss, if according to actual needs, improve rotating speed of motor as 98 revolutions per seconds, then can calculate number of turn W by the polarity area of 6 utmost point motors, at this moment every the number of turn just can be dwindled one times, the sectional area of lead can double simultaneously, the operating current that allows to pass through just can double, and this is called the capacity that has improved with the volume motor, certainly its power consumption also by

Become

(because I has increased by one times)

Use the same method and to design 4 utmost point motors of 300 circular frequencies, change 8800-8900 rev/min of scooter, just capacity can reach with the volume motor 3 times, and this will decide according to the requirement of actual conditions and bearing mechanical aspects, and this is the low frequency electricity another aspect of high-frequency electrical can't be obtained just.

In dissimilar motors, the low frequency high frequency can not be used with, and different because of rotating speed, back-emf is just different, and the voltage that can bear is also different, should use by calculating rationally.

Claims

1. the generator of 300 frequencies that this patent proposed, taken into account a kind of comparatively desirable frequency that factors such as the practical rotating speed restriction of hydroelectric power generation, both technical conditions of thermal power generation and motor are adopted, can save raw material, can save consumes energy again, reduce temperature simultaneously, improve generating efficiency, increase capacity with the volume motor.

This patent has adopted the way of series connection large bulk capacitance to reach these needs of raising power factor (PF) when improving the power output of generator, can form capacitance group by the more electric capacity of parallel connection and accomplish easily.

High-frequency electrical can improve the capacity of unit volume transformer and the capacity of motor.

This patent has been made detailed argumentation to the operation principle of motor in improving the motor operating efficiency, when explaining the reason of the correct use of power factor (PF) in motor, and can not blindly go to improve power factor (PF) (because of power factor (PF) and efficient are inverse relations) in the course of work of motor, thereby draw the high efficiency of high-frequency electrical.